6,15 dialkoxy 5,14 diazo iso violanthrones

ABSTRACT

A novel class of compounds are provided which are 6,15-dialkoxy5,14-diaza-isoviolanthrones. The compounds are synthesized from 1-aza-2-hydroxy-benzanthrone via a novel process comprising bromination of the starting material to form 1-aza-2-hydroxy-3bromo-benzanthrone; the hydroxy group is then alkylated, followed by treatment with sodium sulfide to produce novel intermediates of the invention, 3,3-thio-bis(1-aza-2-alkoxy-benzanthrones). The 6,15-dialkoxy-5,14-diaza-isoviolanthrones of this invention are excellent blue vat dyes, which yield bright blue shades on cellulosic fibers. The dyeings have been found to possess excellent fastness properties.

United States Patent Boffa et al. [451 July 18, 1972 [541 6,15 DIALKOXY5,14 DIAZO ISO [56] References Cited VIOLANTHRONES FOREIGN PATENTS ORAPPLICATIONS Inventors: Giomlflm Both, Novara; Arsento C w, 635,92510/1936 Germany ..260/272 Cogliate; Giampiero Pier'i, Saronno; AngeloManglni; Antonio Tundo, both of Bologna, all of Italy Assignce:Montecatlni Edison S.p.A., Milan, Italy Filed: Aug. 5, 1970 Appl. No.:69,519

Primary Examiner-Donald G. Daus Anorney-Stevens, Davis, Miller & MosherABSTRACT A novel class of compounds are provided which are6,iS-dialkoxy-5,i4diaza-isoviolanthrones. The compounds are synthesizedfrom i-aza-Z-hydroxy-benzanthrone via a novel process comprisingbromination of the starting material to forml-aza-2-hydroxy-3-bromo-benzanthrone; the hydroxy group is thenaikyiated, followed by treatment with sodium sulfide to produce novelintermediates of the invention, 3,3- thi0-bis(i-aza-Z-aikoxy-benzanthrones).

The 6,l5-dialkoxy-5,l4-diaza-isoviolanthrones of this invention areexcellent blue vat dyes, which yield bright blue shades on celluiosicfibers. The dyeings have been found to possess excellent fastnessproperties.

8 Claims, No Drawings This invention relates to novel vat dyes, theiruse and a method for their preparation, including a novel intermediatecompound of that preparation.

Although many compounds have been proposed in the art as vat dyes forcellulosic fibers, efforts continue to discover dyes which productbright blue shades and furthermore have excellent fastness properties.Although blue vat dyes have been known in the art for some time, theincreasing demands of consumers for better fastness properties has madethe search for bright blue dyes having such properties a matter ofincreased importance. Dyes which possess both fastness to light and alsofastness to chlorine and chlorite treatment are thus in much demand.

It is therefore an object of this invention to provide new compoundswhich are suitable for dyeing cellulosic fibers from the vat in brightblue shades and which dyeings have excellent fastness properties.

A further object of this invention is to provide cellulosic fibers dyedin bright blue shades with excellent fastness properties.

A further object of this invention is to provide a novel process for theproduction of blue vat dyes.

A further object of this invention is to provide an improved dyeingprocess for cellulosic fibers.

A further object of this invention is to provide novel intermediatecompounds for the production of blue vat dyes.

The objects of this invention are achieved through the provision ofnovel blue vat dyes which are 6, l -dialkoxy-5, l 4-diaza-isoviolanthrones (which also may be termed 6,-5-dialkoxy-5, I4-diaza-dinaphto l ,2,3-cd;l ,2,3 lmjperylene- 9,1 8-diones) of theformula wherein R is a lower alkyl group of one to four carbon atoms. Assuch alkyl groups may be mentioned methyl, ethyl, npropyl, isopropyl,n-butyl, sec-butyl and tert-butyl.

The 6,15-dialkoxy-5,l4-diaza-isoviolanthrones may be synthesized froml-aza-2-hydroxy-benzanthrone according to the reaction schemeillustrated below. (The starting material, I-aza-2-hydroxy-benzanthrone,may be prepared according to the procedure set forth in copendingapplication Ser. No. 16,989, filed Mar. 5, 1970.)

l-aza-Z-alknxy-B- bromo-benzantnone +KOlI -75 Raw Dye3,3-thiobls(l-aza-2- The synthesis of the 6, l S-dialkoxy-S l 4-diazaisoviolantl-irones is advantageously carried out according to thefollowing procedure:

a. Bromination Into a solution of l-aza-2-hydroxy-benzanthrone inconcentrated sulphuric acid (90-98 percent) a quantity of bromine isadded which is slightly above the stoichiometric amount, preferablyabout 5 to 25 percent. The temperature is raised to 50C and the massallowed to react for an extended period of several hours. Other solventscan be used in place of sulfuric acid such as acetic acid. It has beendiscovered that excellent results are achieved through the use ofconcentrated sulphuric acid which is therefore preferred. The brominederivative thus obtained is isolated by diluting the reaction mass withwater which is thereafter filtered and the resulting cake is washed withwater until the filtrate is neutral. The cake is then dried.

b. Alkylation The bromine derivative of step (a) is converted into thealkoxy derivative by treating at a temperature of between about andabout 150C in an organic solvent with an alkylating agent in thepresence of an acid acceptor. As a preferred organic solvent may bementioned dimethylfonnamide (DMF). Preferred alkylating agents aredialkylsulfates and alkyl toluensulfonates. As a preferred acid acceptormay be mentioned sodium carbonate.

As exemplary of this procedure, the methoxy derivative (R methyl) isobtained by treating the moist paste of the bromo-hydroxy-derivativewith an excess of dimethyl-sulfate (2-4 moles) at a temperature of30-50C, in the presence of an excess of a dilute alkaline hydroxide.

The bromo-alkoxy-derivative may be isolated from the reaction mass bycooling, filtering, and washing first with DMF and then with water. Theproduct may then be dried.

c. Sulfuration An approximately stoichiometric amount of alkalinesulfide or polysulfide, preferably the sodium or potassium derivative,is added to the reaction mars in DMF, which is then heated to 100-l50C.It is preferred that the reaction take place in an inert gas atmosphere,for about 1 to 2 hours.

The mixture is cooled to 30-40C, the formed precipitate is filtered andwashed with the solvent (DMF). The solvent is then removed, the residueis washed with water and thereafter dried in an oven. The sulfurationmay be carried out on the isolated alkoxy-derivative which is suspendedeither in DMF, an alkanol or water.

d. Alkaline condensation The thiobis-(aza-alkoxy-benzanthrone) obtainedin step (c) is subjected to an alkaline condensation by heating underreflux, for an extended period of several hours under a nitrogenatmosphere with an alkali hydroxide in an alkanol solvent. The preferredalkali hydroxide is potassium hydroxide used in excess (-40 moles permole of sulfide). The preferred alkanol solvents are butyl alcohol andisobutyl alcohol.

At the end of the reaction, the solvent is distilled with steam, and airis blown into the hot mass, which is hot-filtered; the cake is washedwith water, until the filtrate is neutral, and then dried at about80120C.

e. Purification The raw dye is purified by boiling for an extendedperiod of several hours in an inert solvent having a boiling point over200C such as nitrobenzene with an alkyltoluensulfonate (about equalweight as the dye) in the presence of an acid acceptor such as anhydroussodium carbonate. The suspension is filtered at a temperature rangingfrom about 20 to 150C. The cake is washed with the solvent used in thepurification, and then the solvent is removed from the cake. The residueis washed with hot water until neutral and it is then dried. Thepurified dyes according to formula I are thus obtained. They appear asblue or violet-blue powders with a melting point over 400C. They arepractically insoluble in all the common organic solvents; in boilingl-chloro-naphthalene they show a low solubility (lower than 1 g/l).

A simplified method for obtaining the dyes consists in carrying out thealkaline melting (d) directly on the bromo-alkoxyderivative; in this waythe sulfuration (c) is not carried out. The raw dye thus obtained ispurified as in (e) and it shows in its pure state the identical chemicalstructure and similar dyeing properties with respect to thecorresponding dye prepared via the above sulfide process.

A dried and ground dye and also the fine paste give a blue vat and dyecellulosic fibers with a bright blue shade after reoxidation in air. Thedyeing method has been described in various publications:

The Society of Dyers and Colorists; the American Association of TextileChemists and Colorists; Color Index, Vol. 2 (1956), page 2,423, DyeingText I;

K. Venkataraman The Chemistry of Synthetic Dyes", Vol. 2 (1952), page872 Academic Press Inc., New York;

(Method IN of I. G. Farbenindustries);

Method RN of ACNA. (Color Index A/Ql Two other methods for theapplication of the dyes l as vat dyes for cotton are described inExamples 6 and 7. These dyes display an excellent fastness to light,comparable, for instance to those of Romantrene BC blue of ACNA (ColorIndex: Vat Blue 6) No. 69,825). The resistances to chlorine and tochlorite are much higher than those of the known blue vat dyes.

As noted above, the compounds of this invention are suitable for dyeingcellulosic fibers. As cellulosic fibers may be mentioned both naturaland synthetic fibers. As natural cellulosic fibers may be mentionedcotton, jute, hemp, and linen. As synthetic cellulosic fibers may bementioned viscose (rayon) and cellulose acetate. The new compounds arealso useful as pigments for coloring paper pulp C (e.g. for soapwrapping papers and printed wall papers), plastics (e.g. rubber andpolyvinyl-chloride), and paints, varnishes, lacquers, and enamels.

The following examples are given for purposes of illustration and arenot to be considered as limiting the scope of the invention, referencebeing had to the appended claims for this purpose.

EXAMPLE 1 16 grams of 1-aza-2-hydroxy-benzanthrone were dissolved atroom temperature in 160 g of 96 percent sulfuric acid. This mixture washeated to 5055C, and then 11.2 g of bromine were fed under stirring. Thewhole mass was kept at 50-55C for 4 hours. The reaction mass was pouredinto water and filtered; the residue was washed with water until thefiltrate was neutral and then dried at -120C.

19.8 g of a violet powder were obtained, consisting of l-aza-2-hydroxy-3-bromo-benzanthrone having a melting point of 285C withdecomposition.

10 g of this intermediate product were dissolved at 6078 C in 56.5 ofdimethyl-formamide (DMF). At this temperature 4.9 g of Na CQ, and 71. gof diethylsulfate were added. The mixture was kept under stirring at6070C for 15 minutes.

The reaction mass contained l-aza-2-ethoxy-3bromobenzanthrone (yellowcrystals from DMF, m. p. l82-l82.5 C).

2. l g of finely ground Na,S at 60 percent were introduced at 607OC inthe reaction mass, nitrogen was fed to saturation and the whole washeated under reflux (about 140C) for 2 hours. After cooling to 30-40Cthe yellowish-orange precipitate thus formed was filtered, washed withcold DMF until obtaining a colorless filtrate. The filtrate was washedwith water and dried at 80-l20C. 7.3 g of a yellowish-pink powder wereobtained, consisting of 3,3-thiobis( 1-aza-2- ethoxybenzanthrone) with amelting point over 360C.

5 g of this intermediate product and 0.5 g of Rodite A (stabilizedsodium hydrosulfite of Montecatini Edison) were introduced into asolution at 8590C of 12 g of KOH in 33 g of isobutanol under stirring.Nitrogen was fed to saturation, followed by heated under reflux (about120C) for 3 hours. The mixture was diluted with g of water and thesolvent was removed by distillation in a steam current.

A flow of hot air was introduced for 30 minutes, the mass was filtered,washed until neutral with boiling water, and dried.

5.3 g of raw dye that had been ground and finely sieved were obtained.The dye was dispersed under vigorous stirring in 60 g of nitrobenzene,2.5 g of ethyl p-toluensulfonate and 1.25 g of anhydrous sodiumcarbonate. The whole was heated at reflux (212C) under a vigorousstirring for 3 hours, and thereafter cooled to 30-40C, and filtered. Theresulting cake was washed with nitrobenzene to obtain a soft bluefiltrate. The solvent was removed from the cake by steam distillationand hot filtered, washed with hot water until the filtrate was neutral,and dried. 3.95 g of the purified dye, 6,15-diethoxy-5,14-diaza-isoviolanthrone (formula I with R C,H,,)where obtained.

This dye, when applied according to the procedure of Example 6, gave adyeing on cotton which was both very deep and of a bright shade. Thedyeing possesses excellent fastness properties.

EXAMPLE 2 16.3 g of l-aza-2-hydroxy-3-bromo-benzanthrone (preparedaccording to Example 1, 10.6 g of Na CO and 21.2 g of n-propylptoluensulfonate were heated for 30 minutes to 100-1l0C. The mixture wascooled to room temperature, filtered, washed with DMF, and then with hotwater, and finally dried.

8 g of a yellow powder found to be of l-aza-2-n-propoxy-3-bromo-benzanthrone was obtained. It had a melting point of l30-132C.

6.62 g of this intermediate product was heated at reflux for 2 hoursunder a nitrogen atmosphere with 1.23 g of Na S at 60 percent in 100 gof DMF. The reaction product yielded, after isolation by cold filtration(according to the procedures described in Example 1 4.73 g of3,3'-thiobis (1-aza-2-npropoxy-benzanthrone), a reddish-yellow powderhaving a melting point 319321C.

From this intermediate, operating exactly as described in Example 1,with the same weight ratios of the corresponding agents used, thepurified dye 6,l5-di-n-propoxy-5,14- diazaisoviolanthrone (formula Iwith R=C -,H,) was obtained.

Dyeings with this compound display similar fastness and a shade greenerthan that of the dye described in Example 1 when applied to cottonaccording to Example 7.

EXAMPLE 3 16.3 g of l-aza-2-hydroxy-3-bromo-benzanthrone (preparedaccording to Example 1, 21.2 g of n-butyl p-toluensulfonate 10.6 g of NaCO and 100 g of DMF were heated for 1 hour to 150C. After cooling to30-40C and isolation according to the procedures described in Example 2,14 g of a yellow powder were obtained, having a melting point of154-l55C with decomposition, consisting ofl-aza-2-butoxy-3-bromo-benzanthrone.

g of this intermediate product was heated at reflux for 2 hours under anitrogen atmosphere in 80 g of DMF in the presence of 1.79 g of Na s at60 percent. There was isolated, operating according to the proceduresdescribed in the preceding example, 7.3 g of 3,3-thiobis(l-aza-Z-butoxybenzanthrone), a yellowish-orange powder having a meltingpoint over 350C. From this inten'nediate product, operating according tothe procedures described in the preceding examples, there was obtained apurified dye, 6,l5-dibutoxy-5,l5- diaza-isoviolanthrone (formula I withR C H The dyeings were similar to the dye described in Example 2, whenapplied to cotton according to the procedures described in Example 7.

EXANIPLE 4 16.3 g of l-aza-2-hydroxy-3-benzanthrone (prepared accordingto Example 1), 21.2 g of isobutyl p-toluensulfonate, 16.6 g Na CO and100 g of DMF were heated for 1 hour to 150C. After cooling to 3040C, 12g a yellowish powder was isolated according to the procedures describedin the foregoing examples, having a melting point of 138-138.5 C. Thecompound was found to be l-aza-2-isobutoxy-3-bromobenzanthrone.

10 g of this intermediate product, heated under reflux for 2 hours undera nitrogen atmosphere in 80 g of DMF containing 1.79 g of Na s at 60percent, yielded, operating according to the procedures described in theforegoing example, 6.9 g of 3- 3'-thiobis(l-aza-2-isobutoxy-benzanthrone), a gold yellow powder having a meltingpoint over 350C.

From this intermediate product operating according to the proceduresdescribed in the foregoing examples, the purified dye was obtained, 6,l5-diisobutoxy-5,14-diazaisoviolanthrone (formula I with R C H whichbehaved as the dye described in Examples 2 and 3, when applied on cottonaccording to the procedure of Example 7.

EXAMPLE 5 g of l-aza-2-hydroxy-3-bromo-benzanthrone was ethoxylated asdescribed in Example 1; the reaction mass was cooled to roomtemperature, filtered, washed with DMF, then with hot water untilneutral and dried. Yellow crystals of 1-aza-2-ethoxy-3-bromo-benzanthrone having a melting point of l82-l 82.5Cwas obtained.

10 a of this intermediate product was heated to reflux temperature undera nitrogen atmosphere for 5 hours, in 70 cc of isobutanol with 4 gRodite A (stabilized sodium hydrosulfite) and 20 g of potassiumhydroxide. After dilution of the reaction mass with 200 cc of water anddistillation of the solvent with a steam current, air was introduced atthe boiling temperature for 10 minutes. Thereafter the mass wasfiltered; the residue was washed with boiling water;until the filtratewas neutral and then dried.

7.8 g of raw dye were obtained which yielded 1 gram of the purified dyeby following the procedure of Example 1 where purification is effectedby boiling in nitrobenzene in the presence of anhydrous Na CO andethyl-p-toluensulfonate. The purified dye is6,l5-diethoxy-5,l4-diaza-isoviolanthrone (formula I with R C H similarto that prepared according to Example 1.

EXAMPLE 6 0.050.l g of 6,lS-diethoxy-S,14-diaza-isoviolanthrone(prepared according to Examples 1 and 5) were mixed with several dropsof denatured ethanol and 3 drops of a 65 percent solution of sodiumsulforicinoleate (the vat-mother liquor).

20 cc of water and 5 cc of NaOH 36 Be were added, then the whole washeated to 6265C, 1 g of sodium hydrosulfite was added cotton was vatdyed for 5 minutes at 6265C. The volume was completed with watercontaining 50 cell of NaOH 36 Be and 10 g/l of sodium hydrosulfite, itwas heated again to 65C and dyed for 40-45 minutes with a ratiocloth/bath equal to l/30.

After air oxidation of the dyed material, this was soaped at the boilingtemperature for 30 minutes with a ratio cloth/bath l/50.

The bath was constituted by a solution containing 2 g/l of DIAPON T(sodium oleyl-methyl-taurinate of Montecatini Edison) and 2 g/l ofsodium carbonate.

After rinse and drying in air, the manufactured article had a very deepand bright blue shade having excellent general fastness properties.

EXAMPLE 7 The procedure of Example 6 was repeated except that thecompound of Example 2, 6,l5-di-n-propoxy- 5,l4diazaisoviolanthrone wasused as the dyestufi'. In addition, 5 cc of pyridine was added to thecondensed solution of the vat mother liquor.

Following this procedure cotton was dyed with the 6,15-din-propoxy-5,14-diaza-isoviolanthrone.

EXAMPLE 8 The procedure of Example 7 was repeated except that thecompound of Example 3 was used as the dye,6,15-di-n-butoxy-5,14-diaza-isoviolanthrone. Similar dyeings on cottonare achieved.

EXAMPLE 9 The procedure of Example 7 was repeated, using as the dye thecompound of Example 4, 6,15-diisobutoxy-5, 14-diazaisoviolanthrone, toproduce dyeings on cotton of comparable quality.

EXAMPLE 10 10 g of l-aza-2-hydroxy-3-bromo-benzanthrone, prepared as inExample 1, was methylated in 56.5 g of DMF and in the presence of 4.9 gof Na CO with 5.8 g of dimethylsulfate, also according to the procedureof Example 1. To the reaction mass containing yellow crystals ofl-aza-2-methoxy-3-bromobenzanthrone (crystals from DMF; m.p. 257260C),2.1 g of finely ground Na s at 60 percent were added at 6070C, nitrogenwas fed to saturation and the mixture was heated at reflux for 2 hours.According to the procedure of Example 1, 6.8 g of yellowish-pink powderwas isolated that was determined to be 3,3'-thiobis(l-aza-2-methoxy-benzanthrone), having a m.p. over 360C.

5 g of this intermediate product, subjected to alkaline melting andsubsequent purification according to the procedures of Example 1,constituted 3.62 g of the purified dye, 6.15-dimethoxy-S,14-diaza-isoviolanthrone (formula I with R CH This dye,applied on cotton according to the procedure of Example 6, or accordingto the principal method RN of ACNA (Color Index, A/Q 1) exhibited thesame characteristics of the dye prepared according to Example 1, butwith a slightly more reddish color.

EXAMPLE 1 l 40 grams of aza-hydroxy-benzanthrone, passed through ascreen with 350 meshes per sq cm, was dissolved in 400 g of concentratedsulphuric acid by admixing them in small portions and under constantstirring. This solution was then stirred at room temperature for another30 minutes, after which 28 g of bromine was added dropwise. Thetemperature was then raised to 50C and the solution was stirred foranother 4 hours. The mixture was poured into about 1 liter of water andice. It was filtered and washed until the acidity disappeared. The pastewas squeezed and suspended in ml of water containing 25 g of potassiumhydroxide. The suspension was then heated under reflux at from 150 to l10C for 105- rninutes while stirring vigorously. Thereupon it wasdiluted with 220 cc of water, cooled to 15C and in 30 minutes 55 g ofdimethylsulfate was introduced. After 4 hours of stirring a further 5 gof potassium hydroxide was added. The mixture was stirred for anotherhour. The mixture was heated for half an hour at 50C and then filteredunder heat. It was washed with boiling water until it was neutral. Themass was then dried in an oven at 100C, and 50 g of the rawbromo-methoxy-derivative was obtained in the form of yellow crystalsfrom dimethylformarnide (DMF) (m.p. 257 to 260C).

into a 100 ml flask, fitted with a stirrer, thermometer, and a coolantwas introduced 29 ml of ethanol and 0.585 g of sulphur. In small pieces,1.05 g of metallic sodium was added so that the temperature did notexceed 70C. When the solution had become clear, the mixture was mixedwith g of bromo-methoxy-aza-benzanthrone, and the mixture was heatedunder reflux for 20 hours with vigorous stirring. The mixture wascooled, diluted with water, filtered, washed and dried. 7.2 g of thecrude 3,3-thiobis-( l-aza-2-methoxybenzanthrone) were obtained.

6.4 g of this product together with 23 g of potassium hydroxidedissolved in 53 ml of isobutanol were heated for 4 hours, under anitrogen atmosphere at 120C. The product was diluted with 250 ml ofwater and for half an hour air was blown into it. The whole was thenfiltered, washed with water until a clear filtrate was obtained, washedagain with acetone and finally dried.

4.5 g of crude 6,15-dimethoxy-5,l4-diaza-isoviolanthrone was obtained.4.4 g of this crude dye was purified by boiling under reflux andstirring with 2.2 g of sodium carbonate, 4.4 g of methylp-toluenesulfonate and 88 ml of nitrobenzene. The reaction water wasremoved by distillation with a small amount of nitrobenzene. The wholewas then filtered at 120C and then washed with nitrobenzene, acetone,acidified water and hot water. 2.8 grams of pure6,l5-dimethoxy-5,14-diazaisoviolanthrone was obtained.

EXAMPLE 12 in a 500 ml glass reactor with anchor type stirrer and athermometer, having a nitrogen atmosphere 15 g of finely powdered sodiumsulfide (a technical product with a purity of 60 percent) were suspendedin 200 ml of 99 percent ethanol. 68 g of a finely powdered1-aza-2-methoxy-3-bromo-benzanthrone prepared according to Example 9 wasthen introduced.

The mixture was then heated under reflux for 24 hours while stirringvigorously. At the end of this reaction the mass was diluted with water,then filtered under a nitrogen atmosphere, washed until a colorlessfiltrate is obtained, and finally dried in an oven at C. 30.5 g of crude3,3'-thiobisl-aza-methoxy-benzanthrone) were obtained.

12.8 g of the sulfide of the previous preparation were finely ground andintroduced under a nitrogen atmosphere into a mixture of 106 ml ofisobutanol and 46 g of potassium hydroxide, heated beforehand to C andvigorously stirred. While stining, the mixture was heated for 4 hours atfrom 120 to C, and at the end of the reaction the mixture was pouredinto water.

Air was injected into the reactor and thereafter the mass was filtered,washed and dried in an oven at 120C. There were obtained 10.8 g of thecrude dye which, when purified as in Example 9, yielded 7.4 g of thepure 6,l5-dimethoxy-5,l4- diaza-isoviolanthrone.

What is claimed is:

l. A compound of the formula

2. The compound of claim 1, wherein R is methyl.
 3. The compound ofclaim 1, wherein R is ethyl.
 4. The compound of claim 1, wherein R isn-propyl.
 5. The compound of claim 1, wherein R is iso-propyl.
 6. Thecompound of claim 1, wherein R is n-butyl.
 7. The compound of claim 1,wherein R is sec-butyl.
 8. The compound of claim 1, wherein R istert-butyl.